Drive apparatus, drive method, and optical device

Abstract

Noise produced during phase-difference changes is minimized without decreasing the responsiveness of a vibration-wave motor. A lens-side MCU for a lens barrel (controls a drive apparatus that applies a drive voltage to the vibration-wave motor by outputting an A-phase drive signal and a B-phase drive signal thereto. The lens-side MCU uses, for example, a drive-voltage setting unit and a duty-cycle change unit to change the drive voltage. Also, the lens-side MCU is provided with a phase-difference change unit that changes the phase difference between the A-phase drive signal and the B-phase drive signal. When driving the vibration-wave motor, the lens-side MCU changes the drive voltage to Vreg, and when the phase-difference change unit is changing the aforementioned phase difference, the drive voltage is changed to V 1 , V 1 being greater than zero and less than Vreg.

The invention claimed is: 
     
       1. An optical device comprising:
 a vibration actuator for which a driving direction changes according to a phase difference between a first drive signal and a second drive signal; 
 a drive apparatus that applies a drive voltage to the vibration actuator by outputting the first drive signal and the second drive signal; 
 a drive voltage change unit that changes the drive voltage; and 
 a phase difference change unit that changes the phase difference, wherein 
 the drive voltage change unit changes the drive voltage to a first voltage in a case of driving the vibration actuator, and changes the drive voltage to a second voltage that is greater than 0 and less than the first voltage in a case of the phase difference change unit changing the phase difference. 
 
     
     
       2. The optical device according to  claim 1 , wherein
 the drive voltage change unit maintains the drive voltage at the second voltage when the phase difference change unit is changing the phase difference, and changes the drive voltage to the first voltage when change of the phase difference by way of the phase difference change unit has completed. 
 
     
     
       3. The optical device according to  claim 1 , further comprising
 a change rate setting unit that sets a change rate upon the phase difference change unit changing the phase difference, based on the first voltage and the second voltage. 
 
     
     
       4. The optical device according to  claim 3 , wherein
 the change rate set by the change rate setting unit is lower when a proportion of the second voltage relative to the first voltage is greater than a predetermined value, than when the proportion of the second voltage relative to the first voltage is smaller than the predetermined value. 
 
     
     
       5. The optical device according to  claim 1 , wherein
 the first drive signal and the second drive signals are pulse signals, and wherein 
 the drive voltage change unit changes the drive voltage by changing a duty cycle of the first drive signal and the second drive signal.